Mass storage media commonly stores information in sequential recording blocks starting from a loading or initial position and proceeding always in one logical direction. A recording block is the smallest unit that can be written and retrieved from the medium. Recording blocks include, but are not limited to control blocks, data blocks and device blocks. A well known example of mass storage is a magnetic tape used in a streaming tape backup application where the entire image of a hard drive is copied onto the tape. The tape is usually loaded starting at one physical end of the tape. Information is then written in the tape in sequential recording blocks as the tape streams toward its far physical end. In some situations an individual tape may be written on once and then archived indefinitely. Tapes in other situations are reused periodically with the new information being written directly over the old information.
It is well known in the art that the storing of additional information along with the customer's information can be helpful in managing the use of tapes and other media. For example, U.S. Pat. No. 5,485,321 issued to Leonhardt et al., on Jan. 16, 1996 discloses identifiers for the user (customer), system and subsystems, application specifications, physical motion data, and header chronology information stored in a user header accompanying a data record. U.S. Pat. 5,619,384 issued to Leonhardt et al., on Apr. 8, 1997 discloses additional header information including block identification (ID), recording block recovery means indicators, recording block length, sequence numbers within recording block groups and block group ID.
Data about the history of the information stored in the recording blocks is traditionally maintained at the file or volume level where it is applied to large groups of recording blocks, instead of at the individual recording block level in each header. File and volume time information usually identifies when the file/volume was created and when it was modified last. Revision information is often maintained within the file/volume, or is embedded in a file/volume name. In any case, the history is applied to all recording blocks equally. There is no mechanism to identify when the history of any one recording block is out of sync with the history of the surrounding files. This creates problems when reading the information from the medium because old information accidently left in the medium may be output during a read process.